This invention concerns installations for exhaust gas recirculation valves. ERG valves are used to control the introduction exhaust gas into the intake manifold of an internal combustion engine in order to reduce engine emissions by lowering peak combustion temperatures reached in the engine cylinders. A first pipe typically extends from the exhaust system to the EGR valve and a second pipe extends from the EGR valve to the intake manifold, with a variable volume of exhaust gas caused to be diverted into the manifold air flow by operation of the EGR valve. The EGR valve is typically installed directly on the engine with a heavy cast iron pedestal.
The high temperatures of the exhaust gas tends to overheat the EGR valve, requiring special designs to avoid early failure of the internal components, namely the electrical solenoid used to operate the valve. The cast iron pedestal also adds appreciably to vehicle weight, which has become of greater concern in recent years.
An engine weight reducing innovation adopted in recent years is the use of molded plastic-composite engine intake manifolds.
This construction of the intake manifold has required particular measures to be taken to allow the hot exhaust gases to be introduced into the air flow while preventing heat damage to the manifold.
Another problem heretofore associated with EGR valves has been the fouling of moving parts in the EGR valve resulting from being exposed to exhaust gas under the pressures existing in the exhaust system. The exhaust gas and contaminants sometimes penetrate clearance spaces when they are exposed to the exhaust gas under the positive pressures of received from the exhaust system, leaving deposits which interfere with proper valve operation.
It is an object of the present invention to provide a lightweight and compact EGR valve installation for a molded intake manifold which avoids excessive heating of the intake manifold structure.
It is another object to provide an EGR valve installation which reduces fouling of the valve components by exposure to exhaust gas.